PB2273: EFFICACY OF OBINUTUZUMAB - BASED REGIMENS IN PATIENTS WITH PREVIOUSLY UNTREATED FOLLICULAR LYMPHOMA: A RETROSPECTIVE OBSERVATIONAL SINGLE-CENTER STUDY
Authors: Nevenka Ridova, Milche Cvetanoski, Sanja Trajkova, Martin Ivanovski, Aleksandra Pivkova Veljanovska, Zlate Stojanoski, Marija Popova Labachevska, Simona Stojanovska Jakimovska, Dushko Dukovski, Lazar Chadievski, Svetlana Krstevska - Balkanov, Mario Jakimovski, Arita Fazliu, Viktorija Kostojchinovska, Gordana Petrushevska, Irina Panovska-Stavridis
Journal: HemaSphere (2023)

Topic: 18. Indolent and mantle-cell non-Hodgkin lymphoma - Clinical Background: Although the addition of anti-CD20 monoclonal antibody, Rituximab (R), to the standard chemotherapy regimens for first-line treatment of follicular lymphoma (FL) and maintenance therapy dramatically improved the overall response and progression free survival (PFS) in the last 20 years, one fifth to one quarter of patients relapse within 2 years of initial treatment. Obinutuzumab (O), the new generation anti-CD20 antibody was introduced in 2016 and O-based immunochemotherapy showed superior results compared to R- based treatment in terms of estimated PFS. As of 2018, O-based chemotherapy became a standard of care for patients with FL at The University Clinic of Hematology - Skopje. Aims: In our study we compared the efficacy and safety of O-based regimens versus R-based regimens in untreated patients with follicular lymphoma, under the routine clinical practice. Methods: This is a retrospective observational study including 132 consecutive newly diagnosed patients with FL, treated at our institution from 2018 to 2022. All patients assigned to different regimens had comparable characteristics, regarding age, gender distribution, lymphoma grade, stage of the disease and ECOG status. Patients were divided in four groups and compared according to regimen, chosen by treatment physician: O-CHOP (48 pts.) vs R-CHOP (35 pts), and O-CVP (26 pts) vs. R-CVP (23pts). MedCalc software was used for comparison tests and survival curves. Results: The mean age of study population was 61 years. More than half were females (57%). The majority of patients (69%) were diagnosed with advanced disease, 40% had stage IV. Patients >65 y had significantly more advanced disease, compared to younger patients (χ2 8,46; p<0.05). Patients treated with O-CHOP had mean age of 57.5y, 63% had advanced disease (stage III and IV) and 60% had high-risk FLIPI score. Cumulative survival at 26 months was 92% in O-CHOP group compared to 82% in R-CHOP group, showing no statistical difference (logrankχ2 0,68, p>0,05). However, higher rate of complete response rates was observed in O-CHOP group (72% vs. 66%). The probability of need of new anti lymphoma treatment at 26 months was insignificantly lower in O-CHOP group (78% vs 76%; Logrank χ2 0,1; p > 0,05). Patients treated with O-CVP had mean age of 62.8y, 65% had advanced disease and 50% had high-risk disease. O-CVP group had significantly better cumulative survival at 26 months than patients treated with R-CVP (92% vs. 69%; logrankχ2 4,2, p<0,05). As both populations had low frequency of death events, we further tested the age and ECOG score as independent factors that may affect the outcome. R-CVP regimen was initiated in older patients at a mean age of 76,8y, compared to 62,8y (u =5,5; p<0,05). No difference was observed in EGOG status of deceased patients. Most frequent side effects were infusion-associated reactions and hematological toxicities, mostly occurring during induction therapy. Infusion associated reactions were noted in 25 patients treated with O, but none of them led to treatment discontinuation. Moderate/severe neutropenia was insignificantly more prevalent in O-group (42% vs. 32.7%). Summary/Conclusion: O-CVP showed superior efficacy and survival rate compared to R-CVP in treatment of previously untreated elderly patients (>65 years) with advanced FL. In younger patients with advanced disease, we observed higher rate of complete response and lower probability of need of new anti-lymphoma treatment in O-CHOP group. However, O-CHOP and R-CHOP showed similar efficacy, mostly explained by the fact of short period of follow-up and that half of the patients are still undergoing maintenance treatment. No unexpected adverse events were noted. Keywords: Survival, Follicular lymphoma, Obinutuzumab, Safety